It's extremely slow to compile and run, so just disable it. For Clang it's
still enabled since that appears to work ok.

This also limits the -fno-sanitize=vptr flag to the Cycles kernel with GCC
and Clang, since it was added specifically to work around an issue there.
This should solve the issue where this flag was used for MSVC as noted in D5149.

Is there any harm to remove if(WITH_COMPILER_ASAN) checks? From historical reasons i didn't use it and instead was passing -fsanitize via CMake's CFlags. If we remove the check the new code will "sanitize" compile times for such manually injected cflags as well?